The manufacturers include Lenovo and Fujitsu, who will use the 65-nanometer custom chip to create their own Windows -based ultrathin notebooks. No date has been announced for the new machines, and Intel and the computer makers have declined to comment.

No Exclusivity Announced

Earlier this month, Apple CEO Steve Jobs unveiled the MacBook Air at the annual Macworld conference. The new laptop is so thin -- three-quarters of an inch at the thickest part -- that it fits into a manila envelope. The svelteness is achieved in part by a special chip Intel designed for the new machine, based on the older Merom line of processors.

During the Macworld presentation, Intel CEO Paul Otellini said Jobs had asked Intel to design a smaller processor. But Intel has not made any public commitment to Apple for exclusivity.

While nearly two-thirds smaller than earlier Meroms and requiring less power , the MacBook Air's Core 2 Duo has reduced performance compared to other Intel Core 2 Duo chips. But Apple has optimized the operating system and other features to maximize performance.

Since small is in, Intel has also been working on other small chips, especially for new generations of handheld devices and the ultra-portable PC that it has helped promote. In particular, it has been developing smaller processors using its new 45-nanometer process.

Difference in Packaging

Martin Reynolds, an analyst with industry research firm Gartner, noted that the difference in the Air chip is in the packaging, not in the chip itself. He added that he expects to see it appear in various computer makers' small devices.

The MacBook Air represents a new level in the game of creating the most portable, most powerful computer. It weighs three pounds, features a 13.3-inch display, a built-in iSight camera, a backlit full-size keyboard, and its Core 2 Duo runs at 1.6 GHz. It is also heir to the multi-touch interface made famous by Apple's iPhone, with a trackpad that, for instance, allows the user to expand a photo with a two-fingered gesture.

Steven Levy of Newsweek, citing the MacBook Air's "gorgeous design," called it "the Audrey Hepburn of laptops." But, unlike the virtually perfect Hepburn, there are several omissions in the Air. Lenovo, Fujitsu or others could exploit these omissions in smaller laptops with the same chip.

Among other things, the Air lacks an optical drive, although there is an option for wirelessly connecting to an external drive. The battery is not removable by the owner and the initial version includes a hard drive of only 80GB.